I've successfuly beaten the gargoyles and Qeelag but it is impossible tho reach Sen's fortress. (had a lot of crashes before but this one is reproducible)
From Undead parish or the forest the game always crash with the same error before reaching the bonfire.

I have joined the save if someone wants to try to past this point.
(I used an eboot cheat but even with the original EBOOT the crash still occurs)